.name-interpolation {
  // If the entire name is interpolated, SassScript is allowed on the
  // right-hand side because we don't know it's a custom property at parse time.
  #{--entire}: 1 + 2;

  // Same if the first hyphen is interpolated.
  -#{-first-hyphen}: 1 + 2;

  // But if the name is interpolated, the right-hand side is static.
  --#{only-name}: 1 + 2;
  // However, interpolation is still allowed on the right-hand side.
  --#{only-name-interp-value}: #{1 + 2};

  // The name can also be partially interpolated.
  --#{initial}-interp: 1 + 2;
  --midd#{le-int}erp: 1 + 2;
  --final-#{interp}: 1 + 2;
  --#{doub}le-int#{erp}: 1 + 2;
}